Modern lubricating oil and fuel oil compositions are complex mixtures of interacting components. No longer is a single material or simple mixture of natural materials appropriate to lubricate a small internal combustion engine. A variety of minor amounts of additives are included in fuel and lubricants to solve particular problems. For instance, dispersants are included in lubricating oil formulations to "disperse" solids formed during engine operation. Basic detergents are included to react with acidic components produced from the sulfur and nitrogen oxides generated during combustion and to prevent rusting of engine parts. Antioxidants and antiwear agents are added to reduce the oxidation rate of the lube base stock and inhibit wearing of the metal surfaces. Friction modifiers may be added to enhance fuel economy. Viscosity modifiers provide correct viscometric balance.
The various carefully tailored components (e.g., detergent, antioxidant, antiwear agent and friction modifiers) of such formulations often interact when mixed in the "concentrates" mentioned above. It is an object of research in this technology to reduce these interactions by careful choice of complementary additives, but that is not always possible. It is an additional object of research in this area to provide "repairs" to an otherwise suitable additive package with multiple utility. That is to say that an auxiliary additive designated as a material to help specifically with interaction problems should desirably have useful antioxidant or dispersion or detergent properties by itself.
The invention here entails the addition of certain amines to lubricating or fuel oil compositions which contain, inter alia, dispersants, detergents and copper antioxidants for the purpose of stabilizing the compositions against phase separation. The added amines may also be suitable as antioxidants in their own right.
European Pat. No. 24,146 relates to copper antioxidants in lubricating oil compositions. The copper antioxidants are disclosed as useful in combination with ashless dispersants, overbased metal detergents and zinc dialkyl dithiophosphate antiwear additives. It is disclosed that while the inclusion of small amounts of the patentee's copper antioxidants generally removes the need for conventionally-used supplementary antioxidants, such supplementary antioxidants could be used especially for oils operating under particularly severe conditions. The disclosed supplementary antioxidants, which are added to the oil in amounts of from 0.5 to 2.5 wt. %, are indicated to include diphenyl amine and alkyl diphenylamines, phenyl-1-naphthyl amine and its alkylated derivatives (e.g., alkylated diphenyl amine, "Octamine").
Copper compounds have been added to such compositions for a variety of other reasons. For instance, the prior art recognizes that copper components per se can be favorable friction reducing agents in certain circumstances. German Democratic Republic Pat. Nos. 145,469 and 145,470 disclose the reduction of wear and friction of iron/iron and iron/bronze friction interfaces using polyol or mineral oil lubricants containing copper compounds such as copper naphthenate, copper octanoate, copper stearate and reaction products of the lubricants themselves with copper, copper oxide and copper salts of inorganic acids. These references indicate that the friction reduction is achieved by the deposition, on the substrate being lubricated, of a film reaction layer of copper with adequate adhesion properties. It is recommended in these references that the concentration of the copper compound in the lubricant provide a copper content of 0.001 to 5 volume % relative to the lubricant. These references however did not evaluate lubricating oil compositions for internal combustion engines.
European published application No. 92,946, published Nov. 7, 1983, is directed to the combination of glycerol esters with oil-soluble copper compounds as fuel economy additives.
Various U.S. Patents suggest the addition of copper bearing materials to oil compositions include:
2,560,542 Bartleson et al. PA1 2,567,023 Morway PA1 3,271,310 LeSuer PA1 4,234,435 Meinhardt et al. PA1 4,552,677 Hopkins
U.S. Pat. Nos. 3,338,832 and 3,281,428 relate to oil soluble N- and B- containing compositions obtained by (i) reacting a substantially hydrocarbon-substituted succinic-acid producing compound (having at least about 50 aliphatic carbons in the hydrocarbon substituent) with at least one-half equivalent of a compound of the formula: ##STR1## wherein R is H or hydrocarbyl and R' is amino, cyano, carbamyl or guanyl, to form an acylated nitrogen intermediate, and (ii) reacting this intermediate with a boron compound. Similar compositions are prepared in U.S. Pat. Nos. 3,282,955 (hydroxyhydrocarbyl-substituted primary and secondary amines) and 3,284,410 (cyanamido compounds of the formula R'N(R)-CN, wherein R is H or alkyl and R' is H, alkyl or guanyl).
U.S. Pat. No. 3,312,619 relates to the reaction products formed by reacting a polyalkenylsuccinic anhydride with a polyalkylene-polyamine, to form a succinimide which is then reacted with e.g., equimolar amounts of, a urea, thiourea of guanidine of the structure: ##STR2## wherein X is O, S or NH.
U.S. Pat. No. 3,711,406 relates to poly (hydroxyalkylated) amines combined with alkaline earth metal carbonates, as rust inhibitors in internal combustion engines, in combination with dispersants, such as overbased sulfonates or phenates or succinimides of alkylene polyamines. U.S. Pat. No. 4,409,000 relates to combinations of certain hydroxy amines and hydrocarbonsoluble carboxylic dispersants as engine and carburetor detergents for normally liquid fuels, and indicates that the dispersant may comprise reactions of a polyalkylene succinimide with a large number of reactive metal compounds, including cupric acetate. The usual weight ratio of the dispersant to the hydroxyamine is disclosed to be between about 1:1 and about 8:1.
None of these references teach the combination of a copper bearing material and an amine in a hydrocarbon base for any reason and certainly not for the purposes of this invention.